The sample is loaded into a weighed sample tube. The sample size is different depending on the expected surface of the sample material. The manufacturer recommends that the sample weight be such that the total surface of the sample in the tube is maintained between 20 and 50 m2. Therefore, the larger the expected sample than the surface, the less sample amount is required. For most catalysts, the amount of sample should be around 0.20 ± 0.02g.
Place the sample tube in the heating pack, fix it with a metal heating wrap, and then attach the sample tube to the degassing station port. After all the samples that need to be degassed are installed at the degassing station, degassing begins. At this time, the indicator light of the selected degassing station is lit, and the pretreatment temperature is set at 300 °C on the digital thermostat of the corresponding degassing station. . If the sample decomposes at 300 ° C, a lower temperature should be set. The degassing temperature should be clearly written to the printed report. After the degassing begins, the computer will automatically control the pressure in the sample tube to gradually decrease and heat up.
For degassing of the powder sample, the following procedure is required to avoid the sample from pumping to the neck and blocking the screen in the degassing station, or even contaminating the valve system to cause air leakage. This method is applied to molecular sieves, light powders and samples that may contain large amounts of water vapor or hydrocarbons. The sample preparation process is as follows:
1. Weigh the empty sample tube together with its filling rod by the same method as above.
2. After loading the sample into the sample tube, insert the filling rod back and fill a small amount of suitable glass wool at the neck of the sample tube.
3. Set the initial temperature to 90 ° C and vacuum at this temperature for 10 ± 1 minute.
4. Fill the temperature to 100 ° C and vacuum for 10 minutes.
5. Repeat step 3 at 110 °C, at which point all water is effectively removed.
6. Increase the temperature to 300 ° C. If the sample adsorbs more impurity gas, it should be degassed under vacuum at 150 ° C for 2-4 hours.
After a minimum of 2 hours of degassing, inspect the sample to ensure complete degassing. Molecular sieves and other hygroscopic samples should be degassed for at least 4 hours. If possible, it is best to get out of the air overnight. The method of checking the degassing effect is to close the manifold and the valve connected to the vacuum pump in the manual state. If the pressure in the sample tube or manifold is stable or rises very slowly, the degassing is complete and can be used for analysis. If not, extend or repeat the degassing process.
Turn off the temperature of the heating pack, gently withdraw the sample tube from the heating pack, and cool the sample tube to room temperature. At this time, the sample tube is backfilled with helium gas, which can then be removed from the degassing station. If a glass stopper is used, remove and immediately cover the same stopper as the empty tube. Weighing to 0.1 mg, minus the gross weight, is the weight of the degassed sample.
Place the sample tube in the heating pack, fix it with a metal heating wrap, and then attach the sample tube to the degassing station port. After all the samples that need to be degassed are installed at the degassing station, degassing begins. At this time, the indicator light of the selected degassing station is lit, and the pretreatment temperature is set at 300 °C on the digital thermostat of the corresponding degassing station. . If the sample decomposes at 300 ° C, a lower temperature should be set. The degassing temperature should be clearly written to the printed report. After the degassing begins, the computer will automatically control the pressure in the sample tube to gradually decrease and heat up.
For degassing of the powder sample, the following procedure is required to avoid the sample from pumping to the neck and blocking the screen in the degassing station, or even contaminating the valve system to cause air leakage. This method is applied to molecular sieves, light powders and samples that may contain large amounts of water vapor or hydrocarbons. The sample preparation process is as follows:
1. Weigh the empty sample tube together with its filling rod by the same method as above.
2. After loading the sample into the sample tube, insert the filling rod back and fill a small amount of suitable glass wool at the neck of the sample tube.
3. Set the initial temperature to 90 ° C and vacuum at this temperature for 10 ± 1 minute.
4. Fill the temperature to 100 ° C and vacuum for 10 minutes.
5. Repeat step 3 at 110 °C, at which point all water is effectively removed.
6. Increase the temperature to 300 ° C. If the sample adsorbs more impurity gas, it should be degassed under vacuum at 150 ° C for 2-4 hours.
After a minimum of 2 hours of degassing, inspect the sample to ensure complete degassing. Molecular sieves and other hygroscopic samples should be degassed for at least 4 hours. If possible, it is best to get out of the air overnight. The method of checking the degassing effect is to close the manifold and the valve connected to the vacuum pump in the manual state. If the pressure in the sample tube or manifold is stable or rises very slowly, the degassing is complete and can be used for analysis. If not, extend or repeat the degassing process.
Turn off the temperature of the heating pack, gently withdraw the sample tube from the heating pack, and cool the sample tube to room temperature. At this time, the sample tube is backfilled with helium gas, which can then be removed from the degassing station. If a glass stopper is used, remove and immediately cover the same stopper as the empty tube. Weighing to 0.1 mg, minus the gross weight, is the weight of the degassed sample.
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